The most frequently cited cause of presistent poverty in the pre-industrail world is population pressue, commonly attributed to Malthus(1778/2007, pg 13): Whocput it succintly:
Depicted in a simple diagram
The most deadly pathogen to hit Europe and Asia
Killed a third of the world population.
In the simple malthusian model, living standards are determined by the intersection of fertility and mortality.
The digram showed that the higher income per capita can be obtained if fertility is restrained.
Malthus considered this possibility, distingusihing it as a preventive check (opposed to a positive check: dieases and starvation) (pg 97)
Two claims:
EMP played an important role in restraining fertility and hence maintaily per capita income(Weak claim)
EMP played an importatn role in the transition to modern economic growth. (Strong claim)
Dennision and Ogilvie(2014)
(Galor and Weil 2000), (Galor,2005), (Galor,2011)